/* package whatever; // don't place package name! */
 
import java.util.*;
import java.lang.*;
import java.io.*;
 
public void replaceSpaces(char[]s, int length)
{
	int count = 0, new_size, i;
	for(i = 0; i < length; i++)
	{
		if(s[i] == ' ')
			count++;
	}
 
	int new_size = length + count * 2;
	s[new_size] = '\0';
 
	for(i = length - 1; i >= 0; i--)
	{
		if(s[i] == ' '){
			s[--new_size] = '0'; 	
			s[--new_size] = '2';
			s[--new_size] = '%';
		}else {
			s[new_size] = s[i];	
			new_size--;
		}
	}
}
 
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		char[] s = "how are you doing?";
		int length = 18;
		replaceSpaces(s, length);
		System.out.print("%s", s);
	}
}